It’s taken nearly two decades, but the Nuclear Regulatory Commission has finally given a green light for the pre-startup test of a “new” reactor at Oak Ridge, Tennessee. Better late than never, perhaps, but the announcement should cause head scratching about why the United States is so far behind the nuclear curve.

The United States produces about one-third of the world’s nuclear-generated electricity, but many of its existing atomic power plants are technologically obsolete. When the Tennessee Valley Authority brings its Watts Bar Unit 2 online, the “Generation II” reactor will already have been surpassed by Generation III reactors in Canada, France and Japan.

Half a century ago, the United States was the only member of the global nuclear club. After detonating atomic bombs at Hiroshima and Nagasaki, Washington’s attention turned to civilian uses of nuclear power. “Atoms for Peace” was a catchphrase of the day. The Cold War was well underway then and civilian reactors were seen as a key producer of nuclear materials destined for military use.